His conviction comes despite a vocal international campaign calling for his freedom.

A Russian military court today sentenced Ukrainian filmmaker Oleg Sentsov to 20 years in prison after convicting him on terror charges.

The sentence is only slightly shorter than the 23 years behind bars demanded by prosecutors last week.

His co-defendant, fellow Ukrainian Alexander Kolchenko, was sentenced to 10 years in prison

Sentsov smiled as the verdict was delivered before he and Kolchenko both sang the Ukrainian national anthem in a courtroom packed with journalists and supporters. Sentsov, still smiling, looked out of the barred cage in which defendants are held in Russian courtrooms and added: "Glory to Ukraine."

Last week, in a defiant final speech, Sentsov told the judge that he did not recognize a court of "occupiers" and called on Russians to have the courage to challenge the Kremlin.

Sentsov's conviction comes despite a vocal international campaign calling for his freedom. Thousands of film professionals have signed a European Film Academy letter to Russian President Vladimir Putin calling for Sentsov's release.

In recent days, Russian filmmakers, noticeably silent on the matter until now, have expressed their support for Sentsov. Director Andrey Zvyagintsev — who earlier this year won a Golden Globe for his controversial film Leviathan — wrote in a letter published in the Novaya Gazeta newspaper on Monday that it was "monstrous to jail a young man, a promising filmmaker for 23 years."

Zvyagintsev called for Russia to "either release [Sentsov] or only try him for what you can prove irrefutably."

Sentsov, who was seized at his home in Crimea in May of last year, had been held for more than a year before his trial began last month at a military court in the southern Russian city of Rostov on Don.

A vocal supporter of the revolution in Ukraine that last year toppled President Viktor Yanukovich, Sentsov had made no secret of his opposition to Russia's illegal seizure of Ukraine's Crimean territory.

But the 39-year-old filmmaker, whose first film, Gamer, was screened at the Rotterdam Film Festival in 2012 to critical acclaim, denied setting a pro-Kremlin party office on fire or plotting to blow up a statue of Vladimir Lenin in Crimea's main city of Simferopol.

Supporters including the European Film Academy say the case is fabricated and that the men have been tried as Russians despite never having applied for Russian citizenship.

Defense lawyers also argued that witnesses had been tortured to produce testimony. Two witnesses, who refused to testify in the face of torture, have already been sentenced to lengthy terms in connection with the case.

Amnesty International last month said there were "serious concerns regarding the two men's rights to a fair trial" due to excessive charges and allegations of torture.

British film producer and deputy EFA chairman Mike Downey told The Hollywood Reporter that the trial had been "a total fiasco, a cross between a series of trumped-up charges and Stalin's 'show trials' of the 1930s. Witnessed have been coerced, evidence tampered with, and the entire case for the prosecution built on a house of cards."

He added: "The EFA will never stop campaigning for Oleg, and we will work tirelessly until he gets the justice he deserves."